import java.io.*;class Person{public void

public void printMyGender(String s){

this.print();

System.out.print(s+" ");

}

class Gender{

String type="gender";

public void print(Person p){p.printMyGender(type);}

}

class Female extends Gender{

public Female(){

type="female";

}

class Male extends Gender{

public Male(){

type="male";

}

class Employee extends Person{

public void print(){

System.out.print("Employee ");}

}

class Manager extends Employee{

public void print(){

System.out.print("Manager ");}

}

public class Test{

public static ">1.import java.io.*;

class Person{

public void print(){System.out.print("Person ");}

public void printMyGender(String s){

this.print();

System.out.print(s+" ");

}

class Gender{

String type="gender";

public void print(Person p){p.printMyGender(type);}

}

class Female extends Gender{

public Female(){

type="female";

}

class Male extends Gender{

public Male(){

type="male";

}

class Employee extends Person{

public void print(){

System.out.print("Employee ");}

}

class Manager extends Employee{

public void print(){

System.out.print("Manager ");}

}

public class Test{

public static

}

class Employee extends Person{

public void print(){

System.out.prin ">2.已知

import java.io.*;

class Person{

public static void print(){System.out.print("Person");}

}

class Employee extends Person{

public void print(){

System.out.prin

}

});

}

public void show(Car c){

c.run();

c.show();

}}

abstract class Car{

public void run(){

System.out.println("car run");

}

public void show(){

System.out.println(getClass().getName());

}}

">3.请写出以下程序运行结果：

package test;

public class Test {

public static void main(String] args) {

Test t = new Test();

t.show(new Car(){

public void run(){

System.out.println("test run");

}

});

}

public void show(Car c){

c.run();

c.show();

}}

abstract class Car{

public void run(){

System.out.println("car run");

}

public void show(){

System.out.println(getClass().getName());

}}

}

class Rectangle extends Shape {

void display() { //实现抽象类的方法

System.out.println("Rectangle");

}

class Triangle extends Shape {

void display() { //实现抽象类的方法

System.out.println("Triangle");

}

public class AbstractClassDemo{

public static void main(String args]){

(new Circle()).display();//定义无名对象来调用对应的display方法

(new Rectangle()).display();

(new Triangle()).display();

}

输出结果是 ?

">4.阅读程序，给出结果：

// AbstractClassDemo.java源代码如下：

abstract class Shape { //定义抽象类Shape和抽象方法display

abstract void display();

}

class Circle extends Shape {

void display() {//实现抽象类的方法

System.out.println("Circle");

}

class Rectangle extends Shape {

void display() { //实现抽象类的方法

System.out.println("Rectangle");

}

class Triangle extends Shape {

void display() { //实现抽象类的方法

System.out.println("Triangle");

}

public class AbstractClassDemo{

public static void main(String args]){

(new Circle()).display();//定义无名对象来调用对应的display方法

(new Rectangle()).display();

(new Triangle()).display();

}

输出结果是 ?

list.add("demo_2");

list.add("demo_3");

ListIterator it = list.listIterator();

while(it.hasPrevious()) {

Object obj = it.previous();

System.out.print(obj+" ");

}

">5.代码三：

import java.util.*;

public class Test03 {

public static void main(String] args) {

ArrayList list = new ArrayList();

list.add("demo_1");

list.add("demo_2");

list.add("demo_3");

ListIterator it = list.listIterator();

while(it.hasPrevious()) {

Object obj = it.previous();

System.out.print(obj+" ");

}

methodA(s);

s=s.replace('e', 'a');

System.out.println(s);

}

public static void methodA(String str){

str+="World";

}

上述代码的运行结果为：（）

">6.当编译并运行下列代码时，其运行结果是什么？

Public class Main{

public static void main(String args]){

String s="Hello";

methodA(s);

s=s.replace('e', 'a');

System.out.println(s);

}

public static void methodA(String str){

str+="World";

}

上述代码的运行结果为：（）

}

class Beta extends Alpha {

String getType() { return "beta"; }

}

class Gamma extends Beta {

String getType() { return "gamma"; }

public static void main(String] args) {

Alpha g1 = new Beta();

Alpha g2 = new Gamma();

System.out.println(g1.getType() + " " + g2.getType());

}

alpha alpha

gamma gamma

alpha beta

beta gamma

class Alpha {

String getType() { return "alpha"; }

}

class Beta extends Alpha {

String getType() { return "beta"; }

}

class Gamma extends Beta {

String getType() { return "gamma"; }

public static void main(String] args) {

Alpha g1 = new Beta();

Alpha g2 = new Gamma();

System.out.println(g1.getType() + " " + g2.getType());

}

alpha alpha

gamma gamma

alpha beta

beta gamma

}

">8.interface Com {

int add(int a, int b);

public static int get(int n){

return n;

}

public default int see(int n){

return n;

}

public default int look(int n){

return n;

}

class A implements Com{

public int add(int a, int b){

return a+b;

}

public int see(int n){

return n+1;

}

public class E {

public static void main(String args]){

A a = new A();

int m = a.add(12,6);

int n =Com.get(12);

int t = a.see(6);

int q = a.look(6);

System.out.printf("%d:%d:%d:%d",m,n,t,q);

}

for (int i=0;i<list.length;i++)

System.out.print(listi]+" ");

System.out.println();

}

public static void main(String] args){

int] list1={0,1,2,3};

int] list2=new intlist1.length];

list2=list1;

PrintLst("数组1",list1);

PrintLst("数组2",list2);

list12]=list12]+10;

PrintLst("修改数组1后，数组2为",list2);

}}

">9.阅读下列程序，并给出程序运行的结果。

Public class CopyArray{

public static void PrintLst(String s,int] list){

System.out.print(s+":");

for (int i=0;i<list.length;i++)

System.out.print(listi]+" ");

System.out.println();

}

public static void main(String] args){

int] list1={0,1,2,3};

int] list2=new intlist1.length];

list2=list1;

PrintLst("数组1",list1);

PrintLst("数组2",list2);

list12]=list12]+10;

PrintLst("修改数组1后，数组2为",list2);

}}

s2 = new String();

s2 = "study hard.";

System.out.print(s1);

System.out.println(s2);

s2 = "learn english, too";

System.out.print(s1);

System.out.println(s2);

s2 = s1 + s2;

System.out.println(s2);

}

">10.6.阅读程序，写出运行结果

public class StringUse {

public static void main(String] args) {

String s1, s2;

s1 = new String("Students should ");

s2 = new String();

s2 = "study hard.";

System.out.print(s1);

System.out.println(s2);

s2 = "learn english, too";

System.out.print(s1);

System.out.println(s2);

s2 = s1 + s2;

System.out.println(s2);

}

">11.请说出下面中【代码】的输出结果

interface Com {

int add(int a,int b);

public static int get(int n){

return n;

}

public default int see(int n){

return n;

}

public default int look(int n){

return n;

}

class A implements Com{

public int add(int a,int b) {

return a+b;

}

public int see(int n){

return n+1;

}

public class Main {

public static void main(String args]) {

A a = new A();

int m = a.add(12,6);

int n =Com.get(12);

int t = a.see(6);

int q = a.look(6);

System.out.printf("%d:%d:%d:%d",m,n,t,q); //【代码】

}

12.下列程序中注释的哪个代码（1、2、3、4）是错误的（无法通过编译）？

abstract class A {

abstract float getFloat (); //1

void f() //2

{ }

}

public class B extends A {

private float m = 1.0f; //3

private float getFloat () //4

{ return m;

}

1

2

3

4

System.out.println(" *** ");

System.out.println(" ***** ");

}

">13.阅读程序，写出下面程序运行结果。

/* Practice1_1.java */

public class Practice1_1 {

public static void main(String] args) {

System.out.println(" * ");

System.out.println(" *** ");

System.out.println(" ***** ");

}

try{

FileOutputStream out=new FileOutputStream(f) ;

out.write(a) ;

out.close () ;

FileInputStream in=new FileInputStream(f);byte ] tom= new byte100];

int m = in.read(tom) ;

String s=new String(tom,0, m) ;

System.out.printf("%d : %s" , m,s);

}catch (IOException e){}

}

">14.阅读以下程序，写出输出结果：

import java.io.*;

public class E{

public static void main(String args]){

int n=-1;

File f =new File("hello.txt") ;byte ] a="abcd".getBytes () ;

try{

FileOutputStream out=new FileOutputStream(f) ;

out.write(a) ;

out.close () ;

FileInputStream in=new FileInputStream(f);byte ] tom= new byte100];

int m = in.read(tom) ;

String s=new String(tom,0, m) ;

System.out.printf("%d : %s" , m,s);

}catch (IOException e){}

}

15.下述哪个方法不可以加人类SubClass? ( )class SupClass{public void methodOne(int i){}public void methodTwo(int i){}public static void methodThree(int i) {}public static void methodForth(int i) {}}class SubClass extends SupClass{:}

A、public static void methodOne(int i){ }

B、public void methodTwo(int i){ }

C、public static void methodThree(int i,intj){ }

D、public static void methodForth(inti){ }

16.下列程序中注释的哪个代码（1、2、3、4）是错误的？

abstract class Takecare {

protected void speakHello() {} //1

public abstract static void cry(); //2

static int f(){ return 0 ;} //3

abstract float g(); //4

}

1

2

3

4

17.下列程序中注释的哪个代码（1、2、3、4）是错误的？

Abstract class Takecare {

protected void speakHello() {} //1

public abstract static void cry(); //2

static int f(){ return 0 ;} //3

abstract float g(); //4

}

1

2

3

4

18.public class Leaf {

private int i = 0; //此属性值用于检验

Leaf increment(){ //定义方法increment()，返回值是Leaf类的对象

i++;

return (1) ;//将当前对象的地址作为返回值返回

}

void print() {

System.out.println(" i = " + i);

}

public static void main(String args]){

Leaf x = (2); //创建Leaf类的对象x

x.increment().increment().increment().print();

}//多次调用方法increment()，返回的都是x的地址，i 值表示调用次数

}

输出结果为 i = (3)